Comment 1 for bug 1764668

Without the fix they were in my case always detected as immediately shut down which likely is wrong and can end in non-clean shutdown even it would have been clean if the guests had some more time.
This was due to the fact that it picked up the empty external var to loop over and then the returned list was obviously empty.

Tests with the fix:

Tested guests not going away (just kill them so early that they do not respond to shutdown yet)
=> ok (took configured max time)

Running guests on default URI: b1, b2, b3
Shutting down guests on default URI...
Starting shutdown on guest: b1
Starting shutdown on guest: b2
Starting shutdown on guest: b3
Waiting for 3 guests to shut down, 120 seconds left
Waiting for 3 guests to shut down, 115 seconds left
Waiting for 3 guests to shut down, 110 seconds left
Waiting for 3 guests to shut down, 105 seconds left
...
Waiting for 3 guests to shut down, 5 seconds left
Timeout expired while shutting down domains

Tested guests going away one by one (just kill them so early that they do not respond to shutdown yet) - and then virsh destroy them over time
=> ok (detected one by one as they should be)

Running guests on default URI: b1, b2, b3
Shutting down guests on default URI...
Starting shutdown on guest: b1
Starting shutdown on guest: b2
Starting shutdown on guest: b3
Waiting for 3 guests to shut down, 120 seconds left
Waiting for 3 guests to shut down, 115 seconds left
Shutdown of guest b2 complete.
Waiting for 2 guests to shut down, 110 seconds left
Waiting for 2 guests to shut down, 105 seconds left
Shutdown of guest b3 complete.
Waiting for 1 guests to shut down, 100 seconds left
Waiting for 1 guests to shut down, 95 seconds left
Waiting for 1 guests to shut down, 90 seconds left
Shutdown of guest b1 complete.

Tested all guests going away immediately (normal guests)
=> ok, detected all in one "loop"

Running guests on default URI: b1, b2, b3
Shutting down guests on default URI...
Starting shutdown on guest: b1
Starting shutdown on guest: b2
Starting shutdown on guest: b3
Waiting for 3 guests to shut down, 120 seconds left
Shutdown of guest b1 complete.
Shutdown of guest b2 complete.
Shutdown of guest b3 complete.

Tested parallel=2 with guests going away one by one (but not all eventually).
=> ok, one down kicked next shutdown
=> ok partial looping did still work to catch timeout

Running guests on default URI: b1, b2, b3
Shutting down guests on default URI...
Starting shutdown on guest: b1
Starting shutdown on guest: b2
Waiting for 3 guests to shut down, 60 seconds left
Shutdown of guest b1 complete.
Starting shutdown on guest: b3
Waiting for 2 guests to shut down, 55 seconds left
...
Waiting for 2 guests to shut down, 5 seconds left
Timeout expired while shutting down domains

Tested parallel=2 with guests going away normally
=> ok, one down kicked next shutdown
=> ok, loop continued and completed

Running guests on default URI: b1, b2, b3
Shutting down guests on default URI...
Starting shutdown on guest: b1
Starting shutdown on guest: b2
Waiting for 3 guests to shut down, 60 seconds left
Shutdown of guest b1 complete.
Shutdown of guest b2 complete.
Starting shutdown on guest: b3
Shutdown of guest b3 complete.

Tested parallel=2 with 5 guests - needing more than 2 loops with guests going away normally
=> ok, one down kicked next shutdown
=> ok, loop continued and completed through all guests

Running guests on default URI: b1, b2, b3, b4, b5
Shutting down guests on default URI...
Starting shutdown on guest: b1
Starting shutdown on guest: b2
Waiting for 5 guests to shut down, 60 seconds left
Shutdown of guest b2 complete.
Starting shutdown on guest: b3
Shutdown of guest b1 complete.
Shutdown of guest b3 complete.
Starting shutdown on guest: b4
Starting shutdown on guest: b5
Shutdown of guest b4 complete.
Shutdown of guest b5 complete.